To change the event setup from the global tag, you need to create a setup source getting the tag you want, and also make sure it is preferred over the global tag.
process.myES = cms.ESSource("PoolDBESSource",
process.CondDBSetup,
connect = cms.string('frontier://FrontierProd/CMS_COND_31X_CSC'), #Change this to wherever the database is
DumpStat=cms.untracked.bool(True),
toGet = cms.VPSet(
cms.PSet(
record = cms.string('CSCBadChambersRcd'), #Change this to the record you want
tag = cms.string('CSCBadChambers_none_FiveLiveME42PLUS_v2') #Change this to the tag you want of the record
)
)
)
#Makes sure myES is used over the global tag
process.esPreferCSCBadChambs = cms.ESPrefer("PoolDBESSource","myES")